Method and apparatus for drying and tentering-drying with radiant heaters and automatic control means



July 10, 1951 c. v. DUNSKI ETIAL 2,559,713

METHOD AND APPARATUS FOR DRYING AND TENTERING-DRYING WITH RADIANT HEATERS AND AUTOMATIC CONTROL MEANS Filed Jan. 22, 1947 4 Sheets-Sheet l i D ia.

Fig 1 #1 3 INVENTORS CHAIM VITAL DUNSKI econ s RIEG T 5,241.

A'c ENTS July 1-0, 1951 c METHOD AND APPARA'T Filed Jan. 22, 1947 V. DUNSKI El AL US FOR DRYING AND TENTERING-DRYING WITH RADIANT HEATERS AND AUTOMATIC CONTROL MEANS Fig. 5

4 Sheets-Sheet 2 INVENTORS CHAIM VITAL DUNSKI GEORGES "ERIE gEGaT By I" AGENTS July 10, 1951 c. v. DUNSKI ETAL 2,559,713

METHOD AND APPARATUS FOR DRYING AND TENTERING-DRYING WITH RADIANT HEATERS AND AUTOMATIC CONTROL MEANS Filed Jan. 22, .1947 4 Sheets-Sheet 3 a 1h m i w 4 H D INVENTORS CHAIM vmu. DUNSKI GEORGES MARI REGOUT BrMBl! d J AGENTS July 10, 1951 C. V. DUNSKI ET AL METHOD AND APPARATUS FOR DRYING AND TENTERING-DRYING WITH RADIANT HEATERS AND AUTOMATIC CONTROL MEANS Filed Jan. 22. 1947 4 Sheets-Sheet 4 INVENTORS CHAIM VITAL DUNSKI GEORGES mm 0007 B I I" AGENTS Patented July 10, 1951 METHOD AND APPARATUS FOR DRYING AND TENTERING-DRYING WITH RADIANT HEATERS MEAN S AND AUTOMATIC CONTROL Chaim Vital Dunski, Liege, and Georges Marie Regout, Heusy, Belgium Application January 22, 1947, Serial No. 723,482 In Belgium August 29, 1946 6 Claims. 1

This invention relates to a method and apparatus for drying and for drying and tenterin fabrics, by means of infra-red radiators, and means for automatic control.

The invention has as an object to causethe drying of a material to which a movement of translation is imparted under conditions permitting rapid and economical action, these conditions being due not only to the efiect of the radiant energy emitted by infra-red radiators, but also to the particular conditions in which the drying takes place.

A second object of the invention is to provide an appropriate process and a machine serving simultaneously for the tentering of fabrics or other products and articles having various but definite widths, and for drying these materials, drying being caused by radiation from the radiators, mainly emitting infra-red rays, the material moving continuously.

The applications of radiators using infra-red rays are numerous, but all of them, although taking into account that the moisture contained in the material to be dried facilitates drying (owing to the power of absorption of these rays by the water or other liquid contained in this material), overlook the fact that the vapor emitted absorbs a considerable part of the radiation before it reaches the material, hence efiiciency is reduced.

On the other hand, the vapor produced by the material in the course of dryin saturates the medium in which the drying takes place and prevents evaporation occurring in a suitable manner. These considerations have led us to enumerate as follows the particular conditions under which drying takes place according to the present invention:

1. The vapor is eliminated by aspiration as it is produced.

2. Formation of the vapor varies in quantity according to whether the material is at the commencement of drying or at a more advanced period, and the drying is thus divided up in the machine by distributing the drying over several distinct chambers.

3. The material is passed into each chamber in the form of a single band over the two faces of which a number of radiators act, the number being variable according to whether the material is at the commencement of the drying or at a later period.

4. The machine is provided with a plurality of aspirating fans or with a conduit forming part of a single aspirator fan for the complete installation, the aspiration being automatically regulated according to the hygrometric condition of the surrounding medium. I

5. In order that the drying may not take place in too dry a medium, injurious to the quality of the material, and in order to permit release of the moisture contained in the core of the material towards the end of the operation, part of the fresh air is aspirated along the material, which condenses a certain quantity of vapor arising from the material. This condensation creates a thin layer of moisture which, reducing the reflective power of the surfaces of the material, on the one hand increases the absorption of the infra-red radiations, especially towards the end of the drying operation, and, on the other hand, facilitates the exchange of heat by conduction between the interior of the material reached by the radiation and the cooled exterior, whereby drying is accelerated at the core of the material. Further, this arrangement cools the material before it leaves the machine.

6. For attaining the conditions of aspiration and conditioning of the surrounding medium, closed chambers are provided. This closing is preferably by means of sheets of polished aluminum or other material, or sheets the surface of which possesses a good co-eflicient of reflection for the infra-red radiation. If desired the exterior of the machine may be thermally insulated.

7. All mechanism necessary for the general control of the machine and of the conveying members is eliminated from the interior of each chamber, the chambers only comprising in the interior the material to be dried, conveying chains. and their guides, which, according to the invention, serve to vary the width of operation in the case of fabric, instead of the movable walls usually employed for this purpose. This arrangement prevents unnecessary absorption of the heat radiated by the radiators. With the same object, the combs or pincers which hold the material, for example the fabric, are insulated from the chains by suitable small strips.

8. The radiant energy emitted by the radiators is determined according to the materials to be treated. Certain inventors who use infra-red radiation for drying cause the power supplied to the radiators to be varied for regulating absorption of the radiation by the material treated. We Consider that this process is not eflicient, since by varying the power supplied, and thus the temperature of the radiant body, the curve of energy emitted as a function of the wave-length of the infra-red radiation is shifted, sometime towards reater wave-lengths and sometimes towards shorter wave-lengths, which modifies the co-emcients of absorption of the material to be dried; also this displacement carries with it an increase or a reduction of the maximum amplitude of this curve, so that regulation of the power supplied to the radiators causes unforeseen effects, contrary to the object to be attained. We have therefore thought it preferable to maintain the power supplied constant in the whole of the machine, taking care to select the quality and the number of radiators per battery necessary in each chamber. This choice has been made on a large test installation for the treatment of fabrics, the detailed description of which with corresponding illustrations will be given below. Nevertheless, the electric circuit for example, has been suitably arranged in order to be able to extinguish or light up automatically some of the radiators in each chamber, so that only the radiators required according to the width of the material are used. since the material may, as has been stated, he of different widths.

The total energy absorbed by the radiators over a given time is thus constant. As various fabrics or materials require different periods of exposure to this constant radiant energy, we cause the speed of movement of the material to vary. This speed variation. can be effected manually, acting on a speed transmission gear, preferably choosing one where the transfer from one speed to another takes place in a continuous, progressive manner. It can also take place automatically by means of known apparatus. There exists for example apparatus based on various principles and indicating the degree of moisture of the fabric or of the material at the outlet of the dryer-tenter. According to whether the fabric has been dried too much or too little, this apparatus acts through appropriate relays on a servo-motor, replacing the manual control of the variable speed transmission gear, in order to reduce or increase the speed of the machine.

In order to economize the power supplying the infra-red radiators and at the same time to preserve the apparatus supplying the radiators and, furthermore, in order not to affect the power supply to the factory, by sudden drops of potential, according to the invention the lighting and extinction of the radiators grouped into batteries in each chamber take place automatically and progressively on the movement of the fabric or material between two groups of radiators, one of which is above and the other below the fabric or material, these two opposite groups forming a battery.

This automatic operation ensures stoppage of the machine both when drying is finished and following on any normal or accidental interruption of the work. This automatic operation is effected through photo-electric cells arranged at the inlet for the fabric or the material into the machine, and also at the outlet.

Other characteristics of the invention will also be referred to in the following description. The machine hereafter described as an example of the invention is an important test installation dealing with the tentering and drying of fabric and is also used to determine in a scientific and exact manner all characteristics of interest in drying by means of radiators.

In the accompanying drawings, which show this installation diagrammatically:

Figure 1 is a side elevation;

Figure 2 is a corresponding front elevation in which certain parts of the mechanism near the front have been omitted for clarity;

Figure 3 is a diagrammatic detail section illustrating the fixing and guiding of the fabric in the interior of the machine;

Figure 4 is a plan;

Figure 5 is a partial diagram of the controls for the mechanism of the installation and the radiator batteries.

The installation comprises three separate chambers I, 2 and 3. The number of these chambers need not be restricted to three and on the other hand the installation may consist of a single chamber. The chamber 2 is fixed vertically at one end of the horizontal chambers I and 3 and could assume a different inclination or it could be omitted. The present arrangement has been adopted because the installation has to serve as a test installation and therefore the radiators had to be easily displaceable in all directions. Due to this arrangement the machine is accessible from all sides and on all its faces.

In the installation shown in the drawings, each chamber consists of a number of upper frames 4 and lower frames 4', all identical, which each support a group of radiant heating bodies or radiators. These two upper and lower groups of radiators form a battery. We will not enterinto details of the construction of these frames, but they can assume any desired form. The group of radiators above, and the group below, the fabric, form a battery indicated in the draw ings by the letter B, followed by a serial number B-I, 3-2, and so on.

Thus, for example, the chamber I (Fig. 1) contains four pairs of frames 4, 4', and thus four pairs of groups of upper and lower radiators; the chamber 2 contains one pair of frames and the chamber 3, three pairs of frames. Commencing with the chamber I, there will be found batteries BI, B--2, 3-3 and 3-4 in chamber I, 13-5 in chamber 2 and 3-6, 3-! and 3-8 in chamber 3 (Figs. 1 and 5).

To form the chambers I, 2 and 3, the frames 4 and 4' are connected together by angle irons 5 and bars I (Fig. 2) In order to partition each chamber, metal plates, preferably of polished aluminum, are used or any other material having a good reflective power for infra-red radiation. These plates may, if desired, be covered on the outside by insulating sheets of cork or the like. All these closing sheets are preferably removable, with the exception of the sheets forming, with respect to the path of movement, of the fabric, transverse walls I0 (Fig. 2), which will be referred to hereafter. The lateral walls of each chamber have been shown in Figure 1, for simplification and clarity of the drawing, as comprising asingle sheet 8, as also the two walls parallel to the fabric by suitable plates 5. Actually, these walls consist of several sheets of suitable dimensions; they are removable and provided with handles (not shown) for ease of manipulation.

As has already been mentioned, all the control mechanism for movement of the fabric is external to the chambers l, 2 and 3. Inside each chamber there are two bars or rails I I of U-shape, movement of which in the transverse direction in each chamber will permit, by means which will hereafter be described, lengthening or shortening of the distance between the two opposite bars II, according to the width of the fabric. The bars extend beyond the chambers I, 2 and 3, and consist of elements II-l. "-2. "-4 and "-4 suitably dimensioned, the whole constituting a unit which we will hereinafter term mobile chassis. The distance between the opposite bars II of each chamber is the same in all three chambers.

Inside each chamber, there are fixed to the bars II, as shown by Fig. 3, members I3 and I of suitable shape which guide chains I8 as wel as at the same time spacing them from one another at a definite distance, which is, as stated, identical in the three chambers. On the edge of each link I5 of each chain I8 there are fixed, according to the fabric to be treated, combs or clips I1, insulated from the link by small strips I6 to prevent. as far as possible the heat produced in the fabric from communicating with the mechanical parts. The bars I I carry, inside each chamber and over the whole length thereof, plates I2; the object of this will be explained below.

The fabric F to be tentered and dried is carried, by rollers R-I to R-B, or directly by the rollers R-1 and R-B, to the base of an inclined plane formed by two small I-shaped beams indicated by I9 (Fig. 4), inside which endless chains I8 move between appropriate guides, driven by chain wheels 20, and carrying combs I1 as already explained. The small beams I9 are crossed towards the base of the inclined plane by a transverse shaft 2I provided at each end with a reverse thread.

Two handwheels 22 and 22 (Fig. 4) mounted on the threads of the shaft 2I are manually rotatable for adjusting the inlet width of the fabric necessary to facilitate hooking of the fabric to the combs I1, and cause a transverse progressive tension of the fabric. Through suitable mechanism, not shown on Fig. 4, one of the handwheels 22 and 22' causes the small beam I9 corresponding thereto to slide, by means of a roller 23,

on a U-shaped pathway 24 fixed to two uprights .5;

25. To permit this adjustment there is provided at the head of each beam I9 a hinged connection 26 between these beams and the elements II-I which extend externally to the chamber I, the rails or side members II. These elements I I-I, like the already mentioned elements I I-2, I I-3 and II-4, extend the rails II at the outlet, and externally of the chambers I, 2 and 3, they support the axles of various parts described hereafter.

As will be seen in Fig. 4, shafts S-I, 8-2, 8-3, 8-4, 8-5 and 8-1 pass through the elements II-I, II-2, II-3 and "-4 and rotate in bearings b-I, b-2, 12-3, 22-4, b-5, 17-6 and b-1, which are fixed to uprights 1 (Figs. 1 and 2). The whole of the uprights I, the longitudinal girders or side members 8, the angle irons 5 and the frames 4 and 4 form, with the cross pieces 38 bracing the uprights 1 (Figs. 1 and 2), the actual frame of the machine.

The shafts S-I to 8-1, drive chain-wheels 29-I t 29-1, which in their turn drive the endless chains I8. The path of the two endless chains I8 is as follows: Starting from the chainwheels 20, which rotate about pivots not shown on the drawing but integral with the small beams I9, the two chains I8 move between upper guides,

\ not shown, integral with the beams I9 and similar to those previously described and shown in Fig. 3. Beyond the guides of the beams I9, the chains wind over chain-wheels 29-I and pass into the chamber I, following guides I3 and I4. Coming out of this chamber, the chains pass over the chain-wheels 29-2 and 29-3, move into the chamber 2 and, following guides similar to the guides I3 and I4, pass over chain-wheels 29-4 and 29-5, and enter the chamber 3 following similar guides. At the outlet from the chamber 3 the chains pass over chain-wheels 29-6, then run under the chain-wheels 29-1, rise to run over the top of the stretcher chain-wheels 3I, adjustable by mechanism not shown in the drawing and integral with the element II-I, follow the chain guides I3 and I4 to the lower part of the beams I9 to move again on to the chain-wheels 2.1. Other chain stretchers are provided on the elements II-2 and II-3, but not shown in the drawing.

The fabric F held by the endless chains I8 is then carried along and follows approximately the same path, which is indicated in Fig. 1 by arrows. Outside the chambers I, 2 and 3 the fabric F is supported by drums D-I to D-1 of wood or brass plate, keyed respectively on the shafts S-I to 8-1 and intended to obviate the normal sagging of the fabric due to its weight. These drums are of a fixed length. To avoid damaging the selvedges of the fabric F, the chain-Wheels 29-I, etc., are provided with rings 32 (Fig. 2) which support the fabric close to the selvedges.

The fabric F is carried by the chains I8 up to a suitable distance between the chain-wheels 29-1 and the stretcher chain-wheels 3|. At this point, the fabric F is detached from the combs or clips I1 by known means not indicated in the drawing, and it then passes between a pressing roller 33 and a driving roller 34, through an automatic folder 35 of known construction and is then folded on a carriage 35 (Fig. 1).

All the movements of the members of the machine are controlled by an electric motor 31 which, through the intermediation of a progressiiely variable speed transmission gear 38, of known construction and for example of two speed reductions 39-I and 39-2, imparts to the shaft 8-1 the speed of rotation desired in each particular case.

At its right-hand extremity, that is to say, on the side remote from the electric motor 31, the shaft S-1 carrying a drum D-1 drives (see Figs. 2 and 4), through a vertical chain transmission 40, the parallel shaft S-I on which is keyed the drum D-I arranged close to the inlet of the chamber I. The other drums D-2 to D-6 are driven by the chains I8.

The mechanism for varying the distance between the combs of two chains I8 according to the width required between selvedges of the fabric is constituted as follows:

On the left-hand side of the principal shaft S-1 and to the rear of the front left-hand upright 1, there is provided a chain transmission 43 driving a transmission device with variable direction of rotation, consisting of three bevel wheels 44a, 44b and 440; these two latter are freely mounted on a longitudinal shaft 45 and a sliding claw sleeve 46 can if desired make them integral with this shaft, under the action of a suitable engagement lever, to give the desired direction of rotation. The longitudinal shaft 45 drives, through sets of bevel pinions 41 and bevel wheels 48, respectively, shafts 49 and 53, which are each provided with left and right hand threads 49a, 49b, 50a and 50b, which pass through nuts 5| or similar members integral with the elements "-3 and II-4. The transmission device 44 may be replaced by an electric motor provided with a switch for changing the direction of rotation. The control of the widening or narrowing of the mobile chains would then be independent of the motor 31.

At its right-hand extremity, the shaft 49 drives, through a vertical transmission chain 52 (Figs. 2 and 4) a shaft 53 which is parallel thereto and is also provided with rightand left-handed threads, which engage in nuts 5| integral with the elements "-2. Similarly, the shaft 59, through a chain transmission 5, drives a shaft 55 also provided with rightand lefthand threads which engage in nuts 5| integral with the elements H-l. This shaft 55 drives, througha chain transmission 56, the screw shaft 2 I already referred to. I

Thus, the two lower parallel shafts 49 and 50 and the two upper parallel shafts 53 and 55, in rotating in the nuts 5|, move inwardly or outwardly, according to the direction of rotation of the shafts, the two movable chassis, with which the nuts 5| are integral, and also the beams 19. The two movable chassis are supported on cross bars by rollers 23 (Figs. 1 and2) Externally of the nuts 5| there are fitted halfbearings of suitable design not shown in the drawing. These half-bearings form forks to support the chain-wheels 29-!1 to 29-1 for rotation of the latter. As these half-bearings are fixed by bolts, rivets or the like to the elements ll-l to I 1-4, the latter elements, together with rails ll, constitute the two movable chassis; consequently, when shafts 49, 50, 53 and 55 rotate to drive the two chassis, they carry with them the chain-wheels. To this end, the chain-wheels, fixed by means of keys to the shafts 8-! to S-I, can move transversely. 7

Thus, by moving the operating lever of the transmission device 44 from its neutral position towards the bevel pinions b or c, the longitudinal shaft 45 is made to rotate either in one direction or the other; the shaft 45 in its turn rotates the shafts l9 and through the bevel wheels and pinions 41 and 48, while the shafts 49 and 50 drive, through the chain transmissions 52, 54 and 56, the shafts 53, 55 and 2|. The simultaneous rotation at the same speed of these five shafts 49, 50, 53, 55 and 2| with screws of the same pitch, causes, as stated, the transverse movement of the movable chassis, which, through the intermediation of the semi-bearings, not shown in the drawing, shift the chain-wheels 29-! to 29-1 on the shafts 8-1 to 3-1 from which derives the movement together or apart of the chains l8 driven by these chain-wheels. The rotation of the shafts S-l to 8-1 causes the rotation of the chain-wheels and the movement of the fabric F, held by combs.

As appears from this explanation and from Figures 1 to 4, the chambers l, 2 and 3 only contain the fabric F and the means of fixing the fabric; all the mechanism operating the chains, as also the moving apart thereof, are outside the drying chambers. This arrangement facilitates supervision of the members and their repair; further, as stated, it avoids loss of heat.

It has been previously explained how the movable chassis and the beams l9 can be spaced apart according to the width of the fabric to be treated. It has also been seen how the introduction of the fabric into the machine can be facilitated and the fabric subjected to progressive tension up to that necessary to give the fabric the required width, by manipulation of the handwheels 22 and 22' and mechanism not shown in the drawing, which draw the beams l9 together at the entry of the fabric into the machine. The

beams N then take up the positions shown Fig. 4 where the progressive widening of the;

fabric F is clearly shown.

It has also been previously stated that the machine would preferably be equipped with two automatic fabric introduoers andbe preceded by selvedge arranging mechanism of known construction, not shown in the drawing. One introducer operates the handwheel 22 and the other the wheel 22', both mounted on the shaft 2| with right-hand and left-hand. threads. As already explained, according to the direction of rotation of the handwheels, the beams l9 approach or recede one from the other. The principle of the automatic introducing mechanism provided is the same as that of any other known automatic introducing device, which could be adapted to the machine according to the invention.

The necessity for obtaining the best possible conditions in the chambers I, 2 and 3 to effect the most rational, rapid and economical tentering and drying has been previously much stressed. A special system of ventilation is used to remove vapor produced on drying in an advantageous manner. As shown, this is carried out by a single fan 6! of the helico-centrifugal type, but a fan for each separate chamber could also be used.

The fan 0| is driven by an electric motor 62 through a belt 63, but this motor can be of variable speed and be coupled directly on to the shaft of the fan. Piping 65 exhausts to atmosphere the vapor produced by the drying and discharged through the fan 6|. On the suction side of the fan a principal conduit 64 divides towards the three chambers. The three bifurcations, (id-i, 54-2 and 64-3, are connected to the chambers at points where the vapor produced on the drying tends to accumulate most. Close to the connection of these bifurcations, and in the interior of pipes Bl-l, 64-2 and 64-3, dampers GE-l, 6'6-2 and 66-3 are located. These dampers are operated through connecting rods by servo-motors B'l-l, 61-2 and 61-3 which rotate through a certain arc to open or close the dampers under the action of thermostats Gil-l, 68-2 and 68-3 influenced by dry bulbs (SS-l, (29-2 and 69-3 and wet bulbs IO-i, 10-2 and 70-3, to regulate the relative moisture of the air in each chamber.

With a fan for each chamber, it would be possible to omit the dampers 68-1, 66-2 and 58-3 and to regulate the suction by causing the speed of each individual motor to vary by the same device as described.

Under these conditions, the fresh air enters almost entirely into each chamber under consideration through the apertures provided in the two walls I0 below the fabric F, absorbing the vapor produced by the lower batteries of radiators, and it surrounds the fabric and the baflle plates 12 in order to absorb at the level of the ceiling of the chamber the vapor coming up from the fabric F. The fresh air will thus have passed close to the sockets of the radiators which gives the double advantage that these sockets are cooled, which prolong the life of the radiators and also that the temperature of the air rises and will have absorbed a greater quantity of vapor per kilogram of fresh air.

The conditioning of the air may now be readily understood. In each of the chambers I, 2 and 3, vapor is produced in proportion to the number of the radiators, the volume of each chamber,

and according to whether the work in each chamber corresponds to an initial, intermediate or final period of drying and tentering. Taking ac count of these particular conditions, each chamber will have an optimum hygrometric state and the necessary quantity of fresh air, resulting from the most suitable position for the damper associated with each chamber. For the choice of this optimum state, it is necessary to bear in mind the observations already pointed out, namely that it is necessary to avoid the accumulation of the vapor of water or other solvent which would easily absorb the infra-red radiations before they reached the fabric, and so diminish their efficiency and cause the surroundings to be saturated.

Due to the dampers, actuated by the servomotors which themselves are actuated by the differential thermostats with wet and dry bulbs. the supply of fresh air in each chamber will be automatically modified according to the change which hastaken place in the surrounding air of each chamber; this varies for each separate chamber. Now, this change in the hygrometric state is a function of the drying, since it is this which produces the vapor. The drying will therefore always take place in a hygrometric medium constant for each chamber, while the medium may of course be different in each chamber. On the other hand, this hygrometric state may be modified at will in each chamber by previously regulating the device consisting of the differential thermostats 68. These are of known construction and lend themselves to all kinds of regulation.

The fabrics treated have a percentage of moisture usually proportional to their dry weight but, as their characteristics are often very different, the duration of dryingwill be different according to these characteristics. As we have previously explained, we maintain the power furnished to the batteries of radiators constant according to the periods of drying, by using more or less radiators per battery. The drying being a combined function of the emissive power of the radiators and of the absorbent power of the fabrics treated, these variations are not therefore proportional to those of the power furnished to the radiators. In order, therefore, to be able to regulate the duration of drying according to the characteristics of the fabrics treated, we cause the speed of displacement of the fabrics to vary. Thus, if one fabric dries more rapidly than another, the time of exposure of this fabric to the radiation is consequently diminished by increasing, as already stated, the speed of movement of the fabric, that is, the speed of the chains l8, which tends to cause the speed of the variable speed transmission 38 to vary. This variation will preferably take place by hand in the case of tentering and drying fabrics of diverse qualities.

Thus, the operator will set the control lever 18 f Fig. 1) according to a pointer moving on a dial; the latter may be graduated directly according to the qualities of the fabrics. The scale of the dial will be calibrated according to preliminary tests carried out for the determination of the time of drying necessary for various qualities of fabrics or materials. This pointer and its dial are not shown on the drawing.

Instead of marking on this scale the speeds of the variable speed transmission for drying the various qualities, there will be marked directly the corresponding times or, preferably again, the

10 qualities of the fabrics corresponding to various speeds of the variable speed transmission. It would also be possible to show by suitable means the movements of the pointer, as also the dial, on a general board, and on a larger scale.

In certain installations where only one kind of fabric is made or only a few kinds of fabrics, it may be advisable to make this variation of the speed of movement of the fabric automatic, depending upon the speed of the variable speed transmission. We have already pointed out the possibility of making the variation of the speed automatic by known apparatus and known means as a function of the degree of humidity of the fabric at the exit from the machine.

One of the most recent of known processes is based on the principle that all fibrous material of whatever origin develops during drying a static electric charge, the amount of which depends in a large measure upon the degree of humidity of the material. This electric charge collected on the tread or on the tissue by means of a charge collector, is carried to a known apparatus which detects and converts it into an indication of humidity. The charge so detected may be amplified and carried through a relay to a servomotor. In our installation, the servo-motor may directly operate the shaft on which the control lever of the variable speed transmission is keyed, after having previously removed the control lever 18 for varying the speed of transmission 38, so as 'to regulate the speed of movement of the fabric according to the degree of humidity of the fabric on emerging from the machine.

On the other hand, the means employed for aspirating a portion of the fresh air in contact with the fabric present the objects and advantages set out below.

As already pointed out, it is very important to remove the water vapor produced in the course of drying as it is formed, in order to avoid adsorption of the radiation by the water vapor; for the good operation of the installation the radiation must be absorbed to the greatest possible extent by the fabric treated, which has led us to design for this installation this process for the automatic removal of the vapor by aspiration of the moist air. But, on the other hand, it is desirable, for obtaining a product good to the touch, that the drying should take place in a moist surrounding. This moist surrounding is created by the fact that the fresh air, sweeping over the fabric by reason of the arrangement of the walls I, as described above, condenses, on the faces of the fabric treated, part of the vapor produced by the action of the radiators. This is particularly advantageous towards the end of the operation of drying, for, as the fabric treated becomes dryer and dryer, its power of absorption of the infrared rays diminishes and its reflective power increases. Now, the moist layers created around the band of fabric by the condensation of vapor due to the fresh air sweeping over the fabric facilitate the absorption and penetration of the infra-red rays to the interior of the fabric to extract the water content. On the other hand, this fresh air in cooling the outer surfaces of the fabric, which, in the interior, is heated by the infra-red rays penetrating theerin, facilitates the exchange of heat by conductors and activates the process of drying. By leaving a part of the last chamber without a radiator, the fresh air efliciently cools the fabric before its exit from the machine.

The electric control of the machine for respond- 11 ing to the objects enumerated is constituted as follows in the case of a three-phase alternating current supply, as indicated in Figure 5.

In this figure, there is shown diagrammatically the control of the motor 31 which serves to control the means effecting the spreading out and the conveyance of the fabric F treated, as also the supply of the radiator batteries. The radiators H of each battery B are properly connected in order to counterbalance the three phases for example in delta. In each upper and lower group of a battery the radiators are located at equal distances from each other; on the other hand, the radiators which are in the upper group of a battery are staggered with respect to those of the lower group. The batteries B-l to B8 consist of radiators covering the minimum width of the fabrics generally treated by the machine, constructed according to the requirements of the factory utilizing it; on the other hand, the batteries B9 and 3-H) extend over the whole length of the machine, and form rows of radiators arranged in parallel and externally of the batteries B| to 3-8 in such manner as to be able to act on fabric exceeding the minimum width of fabric which could be treated.

It should be understood that the number of batteries similar to B-9 and Bl need not be restricted to two.

The supply to the batteries of radiators is via a principal switch MS, while the supply of the motor 31 is via a star-delta switch SD of known construction, which is provided with thermal relays and a supplementary contact I-l normally open in the absence of potential at the terminals.

The supply of each battery depends upon individual contact makers respectively K-l for B-i, K2 for B-2, and so on up to Kl0 for B-IO.

The supply of the excitation currents of the star-delta switch SD for the principal contact maker MS and of the individual switches or contact makers K, and the supply of the other apparatus in the circuit, and to which reference will be made below, takes place either directly by the same mains supplying the motor and the radiators or, as is the case in Fig. 5, through two separate transformers, one of which, T--l,

is connected before the principal contact maker MS, for example, between phases II and III of the mains; the other, T-2, is connected after the same principal contact maker, for example, between phases I and II of the mains.

The other apparatus, of known construction, comprise a clockwork M with a push button PB which will allow automatic engagement of the principal contact maker MS under certain speciflc conditions hereafter mentioned and, after a definite and adjustable time, starting of the principal motor 31; a relay Sl of known construction, with two supplementary contacts, one of which is normally open and the other normally closed in the absence of potential at the terminals of its field coil; a relay S--2 identical with 8-! except that it is also provided with a second contact normally open and with a known device for retarding disengagement (not shown on the drawing) two photo-electric cells of known construction, one of which CE-l is arranged on the path of the fabric before its entry into the chamber I, and the other (IE-2, also arranged on the path of the fabric but at its exit from the last chamber, that is, in the present case, after the exit of the fabric from the chamber 3.

An impulse transmitter IE of known construction supplies current by impulse of definite and adjustable intervals and periods, to a driving control or servo-motor SM which drives a contact slide CB keyed on one end of the servo-motor shaft SM, and limited by its edges b and e. This slide can contact terminals or studs numbered 9 I6, I, 2, 3 8 and 9--i0 arranged on a disc of insulating material P, the two contact studs 9--l 0 being short-circuited. To the terminal of each contact stud 9-l to 98 of the disc P there is connected one of the wires of the excitation circuit of each switch K! to K8. There is also connectsd to the first and the last contact studs 9-l 0 of this disc P a wire from the excitation circuit of K9 and another from the excitation circuit of K-lfl. The excitation circuits of K9 and K-|0 may terminate at separate studs. Also, if the number of radiators in each battery B-9 and Bl0 were sufficiently numerous, these batteries could be subdivided and each sub-division could have its corresponding stud on the disc P.

The supply of excitation currents of the principal apparatus and of the operating and excitation currents of the auxiliary apparatus takes place in the following manner:

The transformer T--l supplies the clockwork M, the excitation coil of the principal switch MS, the circuit of which passes through the relay 3-4 or through the relay S-2 and through the normally open contact 1-! of the star-delta twitch SD. The excitation coils of the relays S--l and S-2 are also supplied by the transformer. T-l, but are responsive to the cells CE-i and CE-2. The transformer T--2 supplies the impulse transmitter IE, the circuit of which passes through a normally open contact of S--l and a normally closed contact of 8-2,

or through a normally closed contact of Si and a normally open contact of S-2. It has been previously noted that on its part the impulse transmitter IE supplies and actuates the servomotor SM carrying the slide CB, the rotation of the latter taking place in the direction of the arrow in Fig. 5, by an angle determined by the duration of each impulse and after intervals, both adjustable by the impulse transmitter. As is seen in Fig. 7 the slide closes, progressively and at equal intervals, the excitation circuits of the contact makers K-l to K-l0, which engage and ccnnect up the batteries of radiators. With each impulse of the impulse transmitter the driving control of the servo-motor SM moves the slide CB by one stud of the disc P and the contact coming from the terminals of the secondary of the transformer T2 can supply the excitation circuits of the contact makersK-i to KI0. Since the edge b of the slide first covers the stud 9H3, contact makers K--9 and K-IO will be the first to engage, and simultaneously, on concition that the keys I4 and I-5 are closed, to which reference will be made below.

Continuing its rotation, the slide CB closes successively all the excitation circuits of the contact makers K--l to KB. After a rotation of about all the contact studs are short-circuited, all the contact makers Kl to Kl0 are engaged, and the slide stops automatically through the intermediation of means which will be described below. A second rotation of the same amplitude and in the same direction, starting from the position in which all the contact makers are engaged, cuts out progressively all the contact makers with the exception of K& and K-W, which disengage last, owing to the second contact stud l3 !l coming after the stud 8 and being in shortcircuit with the stud 9-H preceding the stud I.

Having thus described the electric apparatus in its main outline, the automatic control of the proposed installation takes place in the following manner:

By pressing the push-button PB, the circuit from the secondary of the transformer T-I and supplying the excitation coil of the star-delta switch SD is closed by the clockwork M for a certain adjustable period to allow the fabric to come in front of the cell CE--l. The star-delta switch SD shown diagrammatically in Fig. then engages, starts the motor 31 and closes the supplementary contact I-l, normally open for this same period. Nevertheless, at the end of this period, the switch SD remains engaged, for at the same moment the cell CE-I is obscured by the fabric and the relay associated with this cell, shown diagrammatically in Fig. 5, closes the special three-pole contact I--2 and the current starting from the secondary of T-l passes through this contact 1-4 to the excitation coil of the star-delta switch SD, thus closing it, in spite of the cutting of the circuit through the clockwork. On the other hand, the closing of the three-pole contact I-2 by the cell CEI permits excitation of the relay S-I which then engages, and, as the engagement of the star-delta switch SD has also closed the special contact I-l, the excitation circuit of the principal three-pole switch MS engages and energizes the transformer T2 located after the principal switch MS. The secondary of the transformer T-2 then supplies the impulse transmitter IE by the circuit passing through the normally open contact of S-l, which is closed at this moment and through the normally closed contact of S2, which remains closed, since it is under the control of the second cell, which is at this moment still inactive. The impulse transmitter IE then delivers current by adjustable impulses to the servo-motor SM, which, as stated, causes the contact makers K to engage progressively and at equal intervals.

When the fabric F comes in front of the second cell CE-Z causing the contact 1-3 to close, and allowing the excitation of the switch 8-2 and consequently its engagement, the supply circuit of the impulse transmitter is interrupted;

Sl and 3-! being closed this circuit has a branch passing through a closed contact and an open contact and another branch passing through an open contact and a closed contact. The impulse transmitter IE cannot therefore deliver current to the servo-motor SM and the slide GB is arrested in the position where all the contact studs l to III are short-circuited by it and it thus maintains all the switches K engaged.

At the end of travel of the fabric F, the cell CE-l is the first to be uncovered, and the contact I-2 disengages, as does also the relay S-l. Nevertheless, the principal switch MS, and also the star-delta switch SD, remain engaged due to the arrangement adopted, as shown in Figure '7.

When the end of the cloth enters the apparatus, cell CE-l is uncovered and initiates disengagement of the relay S-l which closes its normally closed contact and allows, since S2 is engaged, a fresh supply by impulse from the impulse transmitter IE to the servo-motor SM, which rotates the slide CB in the direction indicated in Figure 5. This rotation causes the progressive disengagement of the contact makers K commencing with K-l, as has been explained above. Finally, the cell CE-I being no longer obscured by any fabric, causes the relay 8-2 to disengage. Thus, due to the arrangement of the apparatus described by way of example (since the batteries can be controlled for example electrically), the batteries light up progressively and automatically as soon as the fabric F appears in front of them; they are extinguished in the same way with the disappearance of the fabric.

The relay 8-2 is, as already stated, of the retarded disengagement type of known construction, so that as the cell CE: is no longer influenced by the fabric F, the excitation coil of the star-delta switch SD is still supplied owing to the circuit starting from Tl and passing through the first terminal of I--2 towards the first terminal of I-3 and then through a contact normally open, due to the above-mentioned retardation device, to the field coil of SD. Thus, the switches MS and SD only disengage after a certain delay, which can be regulated, in order to give the time necessary for the fabric to pass completely out of the machine.

0n re-engagement, the clockwork, or a similar apparatus, permits the star-delta switch SD to remain engaged for a certain period until the cell CE-I has had suflicient time to act and to cause current to flow in the excitation coil of SD, and so on.

In the event of accidental stoppage of the machine, to avoid injury to the fabric the principal switch Ms disengages, as diagrammatically indicated in Fig. 5. In this case the thermal relay of the star-delta switch SD will cut the field circuit of the latter by opening the contact 1-6 which disengages this switch SD, opening at the same time the contact I-l. This latter being open, the field circuit of the principal switch opens which causes its disengagement and the excitation of all the batteries. In the case of this stoppage which however is very rare, it will be necessary to replace the slide CB at zero. On the other hand, since in the event of accident the cells are obscured by the fabric in the machine, it will be necessary to open the manual switches I| to 1-8 of the supply circuits of each cell, CE| and CE2, respectively, and on starting again after the stoppage the hand switch I| must be closed when the push-button PB is actuated, since the hand switch 1-8 will be immediately closedagain after the engagement of the last contact maker K8.

It is relatively easy to make even this operation automatic and in general the excitation of the cells, as indeed the lighting of the luminous sources associated with the cells and not shown on the drawing, by replacing the hand switch I'! for example by a supplementary contact normally open in the star-delta switch SD, and the hand switch I--8 by one of the contact studs of the disc P and the slide CB. Under these conditions, the cell CE-l and its accessories not shown on the drawing will only commence to act when the machine starts running, that is, when the star-delta switch is engaged; however, the cell CE-2 will only be ready to act after the cell CEI has already commenced.

A further safeguard may be easily provided by means of a luminous signalling arrangement, as follows:

As will be seen in Figure 5, the field circuit of any switch K-l to K8 passes through a normally open contact of the previous switch. On accidental opening of a switch, all those which follow it will disengage, and signalling lamps, for example red, will light up, while the other one, for example, green, will be extinguished. These signalling lamps are supplied through a circuit separate from that of the machine. The first contact maker, the red lamp of which is lit up, is that which is damaged and which consequently has caused disengagement of the others. For extra precaution, all the switches K--l to K-B might be connected to a suitable alarm signal by placing in shunt a contact, normally closed in the absence of potential, of each switch K, on to an alarm bell system. One switch disengaged will suflice to close the alarm circuit.

Another safety device may be obtained if desired by providing the machine with a-photoelectric cell sensitive to infra-red radiation or with a thermometer or a thermo-couple, not shown on the drawing, all of known construction, which will act through a relay, not shown, inserted in the field circuit of the switch K-'I for example. Consequently, if any apparatus shows a temperature nearing the limit permitted for the fabric, it will disengage the relay, which will open the circuit of the switch K-l, and also that of K-8, as has been previously explained. As soon as the temperature is again admissible, the relay will re-engage to cause re-engagement of K-'l and of K8.

The automatic lighting-up of the radiator batteries according to the width of the fabric to be treated, takes place as follows: As stated. the number of radiators arranged in width in each battery B--l to 13-8 is determined by the minimum width of the fabric treated by the factory. For greater widths, there are placed under potential further radiators which are outside this minimum width and which form other batteries, for example B-9 and Bl0. The circuits of these batteries are under the control of the distributor apparatus comprising the servo-motor SM with the slide CB and the insulating disc P, and respectively depending upon switches or interruptors 1-4 and I--5. The arrangement of these latter switches is not shown in the drawing, nevertheless their object is clear and the means for carrying it out are manifold. These switches also may be of difierent forms; for example one arrangement is that in which switches 1-4 and 1-5, in the form of simple contacts, are placed at properly chosen distances and in a suitable manner on a batten or other member with which each tenter-dryer is provided to indicate remotely the width at which the machine is set according to the fabric which is being treated. Thus, as soon as the width of the fabric exceeds approximately the minimum widthcharacteristic of the factory, the switch I-4 is engaged mechanically and in this way, on engagement of the principal switch MS, one or more rows of radiators of each edge and of each face of the fabric will be engaged according to the desired regulation. These radiators will form for example the battery B9. If the width of the fabric becomes still greater than that assumed by the radiators arranged in width in the batteries B--l to B-8, and by the radiators of the battery B-Q, the movable chassis will move further apart, carrying with them the indicating pointers, not shown in the drawing,

of the batten, which serves for stretching out in width the fabric. As previously, the pointer may make contact with the switch I5,'which will engage, on the engagement of the battery 28-), while maintaining the switch I-J closed. This battery contains radiators arranged in rows beyond radiators of the batteries B-l to 16 B! and of the battery 3-9. As has been stated, the number of batteries such as B! and Bl0 is not limited. and further sub-division of these batteries is also possible, taking care to increase accordingly the number of studs carried by the disc P, and to regulate the impulse transmitter IE accordingly.

Starting of the motors 62 of the suction fan Si, or of the several motors if a separate fan for each chamber is used, can also take place automatically. Here, also, automatic working can be carried out in several ways; for example, by connecting the motor directly to the network to the right of the principal switch or through, for example, a retarding relay of known construction, regulated in a suitable manner. With separate fans, each fan could be subject to switches Bl to B-8 in order to start them at the proper time.

Having fully described our invention, what we claim and desire to protect by Letters Patent, is:

1. A method of drying a continuous travelling web of material by infra-red radiation comprising the steps of simultaneously exposing both sides of the web to infra-red rays, varying the quantity of radiation transversely of the web in proportion to the width of the material, continuousiy controlling the speed of travel of the web thereby to control the exposure time in proportion to the weight and quality of the material, the intensity of radiation being kept constant. sucking off the air and water vapor from the vicinity of the web, automatically controlling the rate of sucking off in proportion to the hygrometric condition of the surrounding medium, admitting fresh air to compensate for exhausted air, part of the fresh air being caused to flow along the surface of the web, thereby to cause condensation of vapor issuing from the web and to create a thin layer of humidity increasing the degree of absorption of the rays, the water vapor being progressively sucked oif as it forms, and arresting the operation upon complete drying of the material or upon normal or accidental interruption of the travel of the web.

2. A machine for drying and for drying and -tentering a continuous web of material by infrared radiation comprising a work chamber through which the web to be dried is continuously conveyed, infra-red radiators grouped in batteries on either side of the web, a supply circuit for the radiators, a pair of photo-electric cells controlling the supply circuit, one cell being located at the entrance to and the other at the exit from the machine, the action of said cells being such that when both are unshielded by the web no current is supplied to the radiators, when the entrance cell is shielded and the exit cell unshielded the radiators are progressively supplied, when the two cells are shielded all the radiators are supplied and when the entrance cell is unshielded and the exit cell shielded the radiators progressively cease to be supplied, the supply circuit comprising further a motor control, a slide, an impulse emitter and two relays one of said relays being a time delay relay, a main switch and a plurality of subsidiary switches arranged in such a sequence that the main switch is the first to make contact and thereafter progressively the subsidiary switches when the motor control operates in one direction and that the subsidiary switches break contact first and then the main switch when the motor control rotates in the opposite direction. each subsidiary switch being inserted in the circuit to supply current to one battery of radiators.

3. A machine for drying and for drying and tentering a continuous web of material by infrared radiation comprising a work chamber through which the web is continuously conveyed, a plurality of infra-red radiators arranged in groups on either side of the web and divided into batteries, a supply circuit for the batteries, two photo-electric cells controlling the supply circuit, one of the cells being located at the entrance to and the other at the exit from the machine,

means for exhausting from the chamber thev water vapor formed by evaporation of fluid from the material as it is formed, and means for automatically controlling the exhaust of moist air in proportion to the hygrometric state thereof, said means comprising an exhaust duct leading from the chamber, an exhaust fan connected to the duct, a valve in the duct controlling the output thereof and means comprising a wet bulb, a dry bulb, actuating means for the valve and a servo-motor controlling said actuating means and in turn controlled by said wet bulb and dry bulb.

4. A machine for drying and for drying and tentering a continuous web of material by infrared radiation comprising a work chamber, means for conveying the material continuously through the chamber, a plurality of infra-red radiators grouped on either side of the web in a series of batteries, a current supply circuit for the radiators, two photo-electric cells controlling the supply of current to the circuit, one cell being located at the entrance to and the other at the exit from the machine, means for exhausting from the chamber water vapor formed therein progressively as it is formed, means for automatically controlling the exhaust of moist air from the chamber in accordance with the hygrometric state thereof comprising an exhaust duct leading from the chamber an exhaust fan connected to the duct, a valve controlling the output of the fan and means including a wet bulb, a dry bulb and a servo-motor for actuating the valve, and means for causing fresh air to flow adjacent the surface of the web thereby to create a thin layer of moisture by condensation of the vapor issuing from the material and to increase the absorbent properties of the surfaces of the material, said last named means comprising transverse partitions in the work chamber defining a narrow slit for the passage of the web.

5. A machine for drying and for drying and tentering a continuous web of material by infrared radiation comprising a work chamber through which the web is continuously conveyed, a plurality of radiators arranged on each side of the web and grouped in batteries, a supply circuit for the radiators, two photo-electric cells controlling the supply of current to the circuit and located one at the entrance to and the other at the exit from the machine, said circuit comprising further a motor control, a slide driven by the motor,

an impulse emitter and a time delay switch, means being inserted between the exit cell and the switch for breaking the circuit when the end of the web has passed the last battery of radiators, the time delay being suilicient to enable all of the web to be removed from the work chamber.

6. A machine for drying and for drying and tentering a continuous web of material by infrared radiation comprising a plurality of work chambers in each of which a separate drying step is carried out, the web being conveyed continuously through the chamber, a plurality of infra-red radiators on either side of the web being grouped in each chamber in a plurality of batteries, a supply circuit for the radiators, two photo-electric cells controlling the supply of current to the circuit and located one cell at the entrance to and the other at the exit from the machine, means for varying the number of radiators supplied by the current automatically and transversely of the web in accordance with the width thereof, thereby to regulate the drying time in accordance with the weight and quality of the material, the intensity of radiant energy being maintained constant, means for automatically regulating the exhaust of air from the chambers in accordance with the hygrometric state of the ambient air in each chamber, means for causing at least part of the incoming fresh air to flow adjacent material to be treated, means for stopping the machine when drying is completed or in the event of normal or accidental interruption of the conveyance of the material, and signaling means for luminous and sound indication of accidental stoppage of the machine.

CHAIM VITAL DUNSKI. GEORGES MARIE REGOUT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS Number Name Date 1,339,373 Buensod May 4, 1920 1,463,923 Nelson Aug. 7,, 1923 1,799,300 Kenyon Apr. 7, 1931 1,838,480 Gangler Dec. 29, 1931 1,983,264 Belcher Dec. 4, 1934 2,101,335 Jennings et al Dec. 7, 1937 2,188,401 Crowley Jan. 30, 1940 2,219,213 Swain Oct. 22, 1940 2,244,864 Witham June 10, 1941 2,269,236 Wellmar Jan. 6, 1942 2,300,889 Hamilton Nov. 3, 1942 2,308,239 Bell Jan. 12, 1943 2,352,444 Miller June 27, 1944 2,355,391 Nelson et al Aug. 8, 1944 2,376,207 Tetzlafl et al. May 15, 1945 2,391,195 Ross et al. Dec. 18, 1945 2,420,399 New May 13, 1947 2,445,443 Long July 20,1948 2,451,343 Kunzle Oct. 2, 1948 

